DUCTILE DEFORMATION AND REVISED LITHOSTRATIGRAPHY OF THE MARTONYI SUBUNIT (TORNA UNIT, RUDABANYA MTS.), NORTHEASTERN HUNGARY
Abstract: New structural observations and mapping resulted in the reinterpretation of the Martonyi Subunit, part of the metamorphic Torna Unit, NE Hungary. This low-grade metamorphosed Triassic sequence contains lower Anisian Gutenstein Dolomite, a thin transitional pelagic sequence (Bódvarakó Formation?), Carnian Tornaszentandras Slate, late Carnian-Norian Pötschen Limestone. This stratigraphy is closer to the Bódvarakó windows than to any other Torna subunits. The original sedimentation area could be located on thinned continental crust, relatively close to the oceanic crust of the Meliata branch of the Neotethys. The whole sequence suffered three phases of ductile deformation during Alpine (Cretaceous?) tectogenesis. First, layer-parallel foliation developed (D1), most probably connected to first order nappe stacking. The second deformation phase (D2) is marked by upright, chevron-type folding (D2a). Detachment faults could form at the top of the Gutenstein Dolomite in order to accommodate space problems at fold hinges. The chevron folds were flattened later, during a progressive D2b phase associated with the development of axial plane cleavage and steep reverse faults. The structural style varies depending on locations within folds and on lithology suggesting strain partitioning during the D2b phase. Small kink folds with oblique axes can be related to reactivation of steep faults with oblique slip during the D3 phase, at the transition of brittle-ductile deformation field. The whole unit was thrust upon non-metamorphic unit(s) (D4 brittle phase) due to strike-slip displacement along the Darnó Zone sensu lato during the late Cretaceous and/or Tertiary.
LATE ALBIAN AND CENOMANIAN REDEPOSITED FORAMINIFERA FROM LATE CRETACEOUS-PALEOCENE DEPOSITS OF THE RACA SUBUNIT (MAGURA NAPPE, POLISH WESTERN CARPATHIANS) AND THEIR PALEOGEOGRAPHICAL SIGNIFICANCE
Abstract: Late Albian abundant and diversified foraminifers and calcified radiolaria representing the Planomalina buxtorfi-Rotalipora appenninica Zone, and single Cenomanian planctonic foraminifers have been found as redeposited assemblages within lower-middle Campanian and Paleocene flysch deposits of the Raca Subunit, Magura Nappe, Polish Western Carpathians. The Late Albian foraminifers derived from the source area located at the NW margin of the Magura Basin, whereas the Cenomanian foraminifers derived from the SE periphery of the basin. The presence of such microfauna is interpreted as an occurrence of a submarine plateau with pelagic deposition, under lower neritic-upper bathyal depths in the marginal parts of the Magura Basin, during the Late Albian-Early Cenomanian. This assumption was used for reconstruction of the Late Albian-Early Cenomanian paleogeography of the Magura Basin.
ROZTOKY INTRUSIVE CENTRE IN THE CESKE STREDOHORI MTS.: DIFFERENTIATION, EMPLACEMENT, DISTRIBUTION, ORIENTATION AND AGE OF DYKE SERIES
Abstract: The Roztoky Intrusive Centre (RIC) is formed by a trachytic crater vent, hypabyssal intrusions, together with more than 1000 almost radially arranged dykes and more rare cone sheets. Hypabyssal Weakly Alkaline Series of essexite (33–31 Ma)-monzodiorite (33–30 Ma)-sodalite syenite (30–28 Ma) and two coexisting weakly [camptonite (31 Ma)/gauteite I?-sodalite syenite porphyry-gauteite II? (24 Ma)/trachyte?] and strongly alkaline dyke series [camptonite (28 Ma)/monchiquite (26 Ma)-phonolite/tinguaite (26 Ma)/nepheline syenite porphyry cone sheet (30 Ma)] were recognized. Four principal dyke groups were distinguished: I — lamprophyres (58 %) dominated over II — semilamprophyres (28 %), minor III — basaltic rocks (6 %) and IV — felsic derivatives (9 %). Both radial steeply dipping dykes of lamprophyres, semilamprophyres, basaltic and rare phonolitic rocks and flat dipping cone sheets of trachyte and phonolite/nepheline syenite porphyry are present. Dykes of (semi)lamprophyres, and basaltic rocks show similar preferred strikes of 90° and 0°; felsic derivatives of 330° and 0°. Majority (91–98 %) of dykes (100 % of felsic dykes) are present within a distance of 7 km from the Roztoky main centre. Joint and dyke patterns are controlled by the regional paleostress field existing in the upper crust during magma ascent, by orientations of pre-existing fracture sets in the region and by the superimposed local stress field exerted by the rising intrusion. For the interval of 31–26 Ma in the RIC, the analysis of dyke geometries indicates the dominance of regional stress characterized by N-S tension (lamprophyres ≈ semilamprophyres > basaltic rocks > felsic derivatives).
NANNOPLANKTON OF THE TARKHANIAN DEPOSITS OF THE KERCH PENINSULA (CRIMEA)
Abstract: Tarkhanian calcareous nannoplankton in the area of Crimea have been studied in the sequence of Tarkhan s.str., new stratotype locality Maly Kamyshlak, Skelia section and in the Sokol-60 well (350.0–390.0 m). Associations of nannofossils are assigned to the zone NN5 and can be correlated with the calcareous nannoplankton associations of the Lower Badenian deposits of the Central Paratethys and the Langhian sediments of the Mediterranean area. Paleoreconstructions based on nannofossils have shown that at the beginning of the Tarkhanian transgression a warm sedimentary area with normal salinity was formed. It was connected with the basins of Western Paratethys and there is a possibility of connections with the Indian Ocean or Mediterranean Sea. Quantitative, as well as qualitative impoverishment of nannoplankton points to change of the basin regime, connected with strong terrigenous input, partial isolation and salinity decrease (the time of accumulation of Spirialis clays upper part).
GEOLOGICAL CONDITIONS AND ROCK RADIOACTIVITY IN THE SPELEOTHERAPY MEDICAL FACILITY IN THE ZLATE HORY ORE DISTRICT (THE CZECH REPUBLIC)
Abstract: An abandoned mine located in the Zlate Hory ore district is now used for speleotherapy. A detailed petrographical study along with extensive gamma-ray spectrometry measuring concentrations of naturally occurring radioactive elements (K, U and Th) was conducted in the mine in order to analyze the interrelationship between modal composition and radioactivity of the rocks. Authors warn of a potentially higher concentrations of 222Rn in the subsurface atmosphere of the speleotherapeutic medical facility.